The United States is a nation of immigrants no longer, at least according to the mission statement for the federal agency that issues green cards and visas. The United States Citizenship and Immigration Services revised its mission statement Thursday to remove the phrase “nation of immigrants,” director L. Francis Cissna told staffers in a email. Here’s the old mission statement: “USCIS secures America’s promise as a nation of immigrants by providing accurate and useful information to our customers, granting immigration and citizenship benefits, promoting an awareness and understanding of citizenship, and ensuring the integrity of our immigration system.” And the...